The invention originates in the field of resistance welding technology for use in roll seam welding, projection welding or spot welding and has to do with accommodating components for the operation inside the welding tongs housing.
In U.S. Patent Application 2002/0134763, a device for attaining various welding currents by means of an inverter of simplified construction is shown, and U.S. Patent Application 2001/0038000 discloses a power unit for a resistance welding system for furnishing the requisite electrical energy, in particular the welding current, for the welding operation by means of an inverter current source.
In Japanese Patent Disclosure JP 04037480 A, the inventor, for reducing costs and for a more-compact design, proposes among other things the integration of a power regulator with a welding transformer. Because of the dimensions of the devices for power regulation in modern resistance welding systems (above all when AC technology is employed), the propose combination nevertheless produces a relatively heavy arrangement that is hard to manipulate and because of its weight and the space it requires would hardly be suitable for being carried along, in the housing of a pair of welding tongs, by a welding robot.
In daily use, however, it often happens that the system comprising the welding tongs and the transformer is mounted movably on a robot arm (welding robot). The weight of this arrangement can rapidly amount to 150 kg or more, and the transformer makes up a substantial proportion of the weight. The weight of the entire arrangement is therefore a decisive factor in dimensioning the mechanics and regulating the motion of the welding robot (joints, carrying capacity, acceleration, etc.), and naturally for the costs to be borne as well. The lower the weight, the less stringent are the demands made of the robot mechanics as well.
Triggering the movable system is often attained locally fixedly in conjunction with a central robot controller.